<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>json响应</title>
</head>
<body>
  <div id="box"></div>
</body>
<style>
  #box {
    width: 200px;
    height: 100px;
    border: 1px solid #89b;
  }
</style>
<script>
  const box = document.getElementById('box')
  // 绑定键盘按下事件
  window.onkeydown = function () {
    const xhr = new XMLHttpRequest()
    // 设置响应体数据类型
    xhr.responseType = 'json'
    xhr.open('GET', 'http://127.0.0.1:8000/json-server')
    xhr.send()
    xhr.onreadystatechange = function(){
      if(xhr.readyState === 4) {
        if(xhr.status >= 200 && xhr.status < 300) {
          // box.innerHTML = xhr.response
          // 1. 手动对数据转化
          // let data = JSON.parse(xhr.response)
          // box.innerHTML = data.name
          // 2. 自动转化，设置响应体数据类型xhr.responseType = 'json'
          box.innerHTML = xhr.response.name
        }
      }
    }
  } 
</script>
</html>